MAN Diesel engine from 1907 "DM 2 * 100"

[kutzdibutz]

Nick,
WOW! That is some marvellous work! :bow:
Makes me want to start casting as well! Must be quite a joy to dig this parts out of the sand.

With this precision and finish you could cast cogs for watches!

Cheers, Karsten

 

[MuellerNick]

Castings #3 & #4:
Camshaft mount. Basically, these are mirrored parts. Left and right. But one has a few details added.
First, I tried this casting with a split pattern. But after I didn't get the pattern out of the sand for four times, I converted it to use a core.

The left and simpler one as cast.


And the pattern. Needs one core. The core is mirrored too. I'll go into more detail about the core in the right casting.


The right camshaft mount.


Other view into the recess.


Detailed view of the added detail.


Same detail, but with the tiny core in place.


Pattern for the right one,


Detail where the tiny core goes to.

follow up in a few minutes ...

 

[MuellerNick]

The core and core box:

Core box (with just the lower half).


Core in the core box and with the brass insert. The split plane are in fact two planes, so that's what the brass insert is good for.


Core. What you see near my pinky (concave part) and looks like some burr/flash, is in fact the inner radius of the pocket in this casting.



This is the radius. Well, at a different spot. Where the radius ends, the core ends too. You can see a bit of flash in the casting. Inserting this core and pushing it down just the right amount is a bit of a lottery. But it works most of the time.


The core sticking in the upper half of the core box, with the pocket for the brass insert (obviously without the insert). Here you can see how the insert makes the second splitting plane.

Part #5:
That goes on top of part 3 & 4 and is the cover of the camshaft bearing.

Easy!

Edit:
The silvery color on some of the core parts is a wash. Alcohol wash in fact. Makes a bit finer finish. The sand I do have for the cores is not as fine as the oil bound sand. IIRC, it is 0.036 mm average size. Already makes a visible difference.


Nick

 

[ksor]

A very fine job you did here !

 

[mu38&Bg#]

Nick do you use new ingot for castings? Or do you recycle aluminum engine heads and such? Your castings are always spectacular. I've been following your youtube for some time. I see European castings are often marked with the alloy used, at least in some of the BMW parts I've handled.

 

[MuellerNick]

Greg, I'm just recycling (I'm green ) scrap aluminium castings. Whatever it is. Cylinder heads, rims, gear boxes, ... you name it, I melt it!
The most common alloy is something near AlSi8. That's what the big foundries do have in their standard program. If it is AlSi12 (detailed castings), it doesn't hurt.
A few of the castings are marked.

I make ingots out of them, so they do get cleaner. I also do use degassing tablets and a skimming salt (for the dross).
Those degassing-tables are getting hard to obtain, so I'll have to switch to nitrogen (argon would work too, but is more expensive).

Nick

 

[MuellerNick]

Castings #6 & #7: The outer generator bearing housing ...

The lower part (runner and gate still in place).


Look into the upper cavity


and the lower cavity.


The upper half of the bearing housing, with the core still in place.


Pattern for the lower half. Casting position is upside down.


Core and core box #1. Core is mirrored, halves glued together.


Core and core box #2 for the lower half. Also symmetrical.


Here is a cut-though of a previous version of the lower half. Where I marked with a red felt, there was too much material.


Here's the result of the shrinkage on the outside. I couldn't get rid of the shrinkage, no matter how I placed the gates. And I don't know what putty has to do on castings. So I changed the upper core (core #2), to leave less material in that place.


That's the core box of the previous version. If you compare both cores, you see what made the difference.

Note:
Do NOT think that I cast parts in the speed I present them here. Some patterns take a week to make, some take several tries to get them running. Some are a pain to get out of the sand. Even how you rattle them free makes a difference.
I do have a pattern that I may only rattle in one direction. Perpendicular to that, the sand breaks. Took some time to find that out ... :fan:

Nick

 

[jasonh]

Nick:

Thanks for posting this. I cast parts as well, but I'm not at your level (yet!). Watching your video gave me 3-4 ideas to try out that might improve the quality of my castings.

Question - Magnesium in the riser? The Mg burns and keeps the riser hot while the casting solidifies, thereby avoiding shrinkage? Is that right?

Thanks- Jason H

 

[MuellerNick]

The Mg burns and keeps the riser hot while the casting solidifies, thereby avoiding shrinkage? Is that right?

Yep! Keeping it liquid for a longer time, so it can feed and solidifies as the last part.
But it is not pure magnesium! It only contains about 30% and something (whatever) that slows down the burning. It is a ready-made product.

Anyhow, it is more of a last resort, if all fails. I'm only using it with the A-frame, not on other parts.
You could blame me for not making a better mold design. But with the A-frame, there were only a few places to place a riser that would not show later. I don't want to do any work on visible surfaces. Also, I won't use filler on my castings. That destroys the visual appearance of a casting (in my eyes).

The Deckel FP!s (other thread of mine), were just slightly blasted with glass beads and then directly spray painted with a 2K-paint. So that works.


Nick

 

[MuellerNick]

I had a new break-through today.

Making tiny parts in sand is a real pain. So I decided to make the moulds out of core sand, and embed these molds into oil bound sand (for the runners etc.).
That worked to some extent, but the failures still were too many. And it didn't work for very intricate parts.

So I experimented with pressure casting into core sand moulds. But that failed miserably. With hot chamber, the plunger seized, with cold chamber, the metal froze.

So I thought about vacuum assisted casting. But I didn't have a vacuum pump with enough volume and pressure. When I went buying my milk at the farmer over the road, the vane pum in his milking chamber hit my eyes. Next day to the service tech for milking stations in the next village, and home I went with a pump.

Made a vacuum chamber out of MDF and cast a lid. The first tries worked somehow, but the surface was terrible. The molten aluminium diffused into the sand. Some moulds bursted (within the box, so no harm).

So I needed some simple means to adjust the pressure. This is the result:


The vacuum chamber


The lid. The array of M6 screws is for adjusting the pressure by experimenting. In the center, the molten metal is poured in.


Back of the lid and how a mould is fixed.

Results:

This is the batch of tries I made today. Only the pour in the lower right has some shrinkage, but the temperature was too low.
The others came out real nice.

So I have casting #7. A lid for a bearing housing.


Thickness is only 2 mm.


From the rear with the gate sawn off. The "A" is from an experiment with the wash. Just to know witch one went where.


Casting in the mold, one half hammered off.


Seen from the rear, with the "runner" still in place.


Cores and core boxes involved for that casting.


A similar, albeit a bit bigger mould assembled.


Nick

 

[MuellerNick]

I made a cut-through with casting #7, the lid for a bearing housing.
This casting is a reject from previous trials. Way too rough surface.





1: 2 mm thickness
2: 0.5 * 0.5 mm
3: 1.5 mm

I get so few comments. So leave my explanations/pictures no questions, or am I teaching granny blowing eggs?


Nick

 

[Cogsy]

I made a cut-through with casting #7, the lid for a bearing housing.
I get so few comments. So leave my explanations/pictures no questions, or am I teaching granny blowing eggs?

Personally, this stuff just blows my mind! From the first post of all the dots to the intricate castings, I'm in awe. So I just sit back and watch with interest, but I really don't have anything to add.

Nice work though and please keep posting!

 

[lee9966]

I find your work amazing. It is great to see such nice work along with explanations. Keep going!

Lee

 

[kvom]

Rather than comments, watch the number of views on this thread. That's what shows real interest.

Keep up the good work!

 

[MuellerNick]

So I made a video on this lazy sunday afternoon:

[ame="http://www.youtube.com/watch?v=QijGV2G26JI"]Vacuum supported casting[/ame]

Nick

 

[AussieJimG]

Cogsy and Kvom have said it all. I am watching as well but I have nothing to add.

But one question: What is the moulding material in the video? I thought moulding sand was much coarser and more brittle.

Thanks for the journey, I am enjoying it.

Jim

 

[gus]

Hi Nick,
Did have in-gate shrinking and pulling castings. Thanks for the tip. Never thought of using magnezium powder.
Done some gravity casting into casting iron molds in 1980s and 90s. Was never a professional Aluminium Foundry Man. My uncles were doing it and they made it look so easy. Seen car engine pistons casted in China and again they made it look so easy.

 

[MuellerNick]

What is the moulding material in the video? I thought moulding sand was much coarser and more brittle.

That is core sand/material.
Cores are made either cold box or hot box. That means, that the mould for the core is cold, or is heated up. In the later, the heat is what starts the binding reaction. Hot box cores have that typical burnt yellow to brown color.
I'm using cold box (no heat resistant core sand moulds required). Typical binders are (were) weed, molasses, water glass, or polyurethane.
With water glass or PU, the binding reaction is started with a gas. Weed, molasses are moulded cold, removed from the mould and then baked.
I'm using PU. The cores with PU are quite tuff, as you can see when hammering them apart.
Grain size of my core sand is 0.035 (or so) mm.

My uncles were doing it and they made it look so easy.

Casting isn't very complicated. As long as you know all the tricks.


Thanks for the likes!

Nick

 

[gus]

Yes.All the trade secrets.Too bad, in my hour of need,all my aluminium/brass foundry uncles were dead and gone.They were old tradesmen who read temperatures by eyeball.No pyrometers.
Happened to be visiting Shanghai Heavy Air Compressor Plant,China 1989. Sneaked into the foundry shop,to watch them pouring aluminium pistons in C.I.Molds.Was an asset when you could speak your mother dialect.Got all my questions answered. Melt temperature,pouring temperature,cast iron mold temperature etc. Degassing chemicals and grain refining chemicals.Dinner and beer sessions yielded so much info that poor Gus could not retain.They even gave me tips to cast brass,bronze etc.

I did think about casting brass abd bronze but the higher temperatures put me off.

Foundry Supply salesman also gave some tips too.

After some trial and error and tears ,got the first batch of gravity cast trap bodies out for machining. Must say again Gus know nuts about aluminium casting.Had a major order which require 200 pcs "Champion" Condensate traps.Kept a reject demo sample to celebrate US$100,000order completion.Foto attached.

Nick,You are my maestro. Now thinking about building a very mini aluminium furnace.Your expertise is sought.

 

[skyline1]

You can't beat the old MK1 eyeball Gus